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RFC 1447 - 2.6. The MIB View Database Group

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### 2.6. The MIB View Database Group

       -- the MIB view database group

       snmpViews      OBJECT IDENTIFIER ::= { partyMIBObjects 4 }

       viewTable OBJECT-TYPE
           SYNTAX      SEQUENCE OF ViewEntry
           MAX-ACCESS  not-accessible
           STATUS      current
           DESCRIPTION
                   "Locally held information about the MIB views
                   known to this SNMPv2 entity.

                   Each SNMPv2 context which is locally accessible
                   has a single MIB view which is defined by two
                   collections of view subtrees: the included view
                   subtrees, and the excluded view subtrees.  Every
                   such subtree, both included and excluded, is
                   defined in this table.

                   To determine if a particular object instance is in
                   a particular MIB view, compare the object
                   instance's OBJECT IDENTIFIER with each of the MIB
                   view's entries in this table.  If none match, then
                   the object instance is not in the MIB view.  If
                   one or more match, then the object instance is
                   included in, or excluded from, the MIB view
                   according to the value of viewType in the entry
                   whose value of viewSubtree has the most sub-
                   identifiers.  If multiple entries match and have
                   the same number of sub-identifiers, then the
                   lexicographically greatest instance of viewType
                   determines the inclusion or exclusion.

                   An object instance's OBJECT IDENTIFIER X matches
                   an entry in this table when the number of sub-
                   identifiers in X is at least as many as in the
                   value of viewSubtree for the entry, and each sub-
                   identifier in the value of viewSubtree matches its
                   corresponding sub-identifier in X.  Two sub-
                   identifiers match either if the corresponding bit
                   of viewMask is zero (the 'wild card' value), or if
                   they are equal.

                   Due to this 'wild card' capability, we introduce
                   the term, a 'family' of view subtrees, to refer to
                   the set of subtrees defined by a particular
                   combination of values of viewSubtree and viewMask.
                   In the case where no 'wild card' is defined in
                   viewMask, the family of view subtrees reduces to a
                   single view subtree."
           ::= { snmpViews 1 }

       viewEntry OBJECT-TYPE
           SYNTAX      ViewEntry
           MAX-ACCESS  not-accessible
           STATUS      current
           DESCRIPTION
                   "Information on a particular family of view
                   subtrees included in or excluded from a particular
                   SNMPv2 context's MIB view.

                   Implementations must not restrict the number of
                   families of view subtrees for a given MIB view,
                   except as dictated by resource constraints on the
                   overall number of entries in the viewTable."
           INDEX      { viewIndex, IMPLIED viewSubtree }
           ::= { viewTable 1 }

       ViewEntry ::=
           SEQUENCE {
               viewIndex        INTEGER,
               viewSubtree      OBJECT IDENTIFIER,
               viewMask         OCTET STRING,
               viewType         INTEGER,
               viewStorageType  StorageType,
               viewStatus       RowStatus
           }

       viewIndex OBJECT-TYPE
           SYNTAX      INTEGER (1..65535)
           MAX-ACCESS  not-accessible
           STATUS      current
           DESCRIPTION
                   "A unique value for each MIB view.  The value for
                   each MIB view must remain constant at least from
                   one re-initialization of the entity's network
                   management system to the next re-initialization."
           ::= { viewEntry 1 }

       viewSubtree OBJECT-TYPE
           SYNTAX      OBJECT IDENTIFIER
           MAX-ACCESS  not-accessible
           STATUS      current
           DESCRIPTION
                   "A MIB subtree."
           ::= { viewEntry 2 }

       viewMask OBJECT-TYPE
           SYNTAX      OCTET STRING (SIZE (0..16))
           MAX-ACCESS  read-create
           STATUS      current
           DESCRIPTION
                   "The bit mask which, in combination with the
                   corresponding instance of viewSubtree, defines a
                   family of view subtrees.

                   Each bit of this bit mask corresponds to a sub-
                   identifier of viewSubtree, with the most
                   significant bit of the i-th octet of this octet
                   string value (extended if necessary, see below)
                   corresponding to the (8*i - 7)-th sub-identifier,
                   and the least significant bit of the i-th octet of
                   this octet string corresponding to the (8*i)-th
                   sub-identifier, where i is in the range 1 through
                   16.

                   Each bit of this bit mask specifies whether or not
                   the corresponding sub-identifiers must match when
                   determining if an OBJECT IDENTIFIER is in this
                   family of view subtrees; a '1' indicates that an
                   exact match must occur; a '0' indicates 'wild
                   card', i.e., any sub-identifier value matches.

                   Thus, the OBJECT IDENTIFIER X of an object
                   instance is contained in a family of view subtrees
                   if the following criteria are met:

                        for each sub-identifier of the value of
                        viewSubtree, either:

                             the i-th bit of viewMask is 0, or

                             the i-th sub-identifier of X is equal to
                             the i-th sub-identifier of the value of
                             viewSubtree.

                   If the value of this bit mask is M bits long and
                   there are more than M sub-identifiers in the
                   corresponding instance of viewSubtree, then the
                   bit mask is extended with 1's to be the required
                   length.

                   Note that when the value of this object is the
                   zero-length string, this extension rule results in
                   a mask of all-1's being used (i.e., no 'wild
                   card'), and the family of view subtrees is the one
                   view subtree uniquely identified by the
                   corresponding instance of viewSubtree."
           DEFVAL      { ''H }
           ::= { viewEntry 3 }

       viewType OBJECT-TYPE
           SYNTAX      INTEGER  {
                           included(1),
                           excluded(2)
                       }
           MAX-ACCESS  read-create
           STATUS      current
           DESCRIPTION
                   "The status of a particular family of view
                   subtrees within the particular SNMPv2 context's
                   MIB view.  The value 'included(1)' indicates that
                   the corresponding instances of viewSubtree and
                   viewMask define a family of view subtrees included
                   in the MIB view.  The  value 'excluded(2)'
                   indicates that the corresponding instances of
                   viewSubtree and viewMask define a family of view
                   subtrees excluded from the MIB view."
           DEFVAL      { included }
           ::= { viewEntry 4 }

       viewStorageType OBJECT-TYPE
           SYNTAX      StorageType
           MAX-ACCESS  read-create
           STATUS      current
           DESCRIPTION
                   "The storage type for this conceptual row in the
                   viewTable."
           DEFVAL      { nonVolatile }
           ::= { viewEntry 5 }

       viewStatus OBJECT-TYPE
           SYNTAX      RowStatus
           MAX-ACCESS  read-create
           STATUS      current
           DESCRIPTION
                   "The status of this conceptual row in the
                   viewTable."
           ::= { viewEntry 6 }

Next: 2.7. Conformance Information

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RFC 1447 - 2.6. The MIB View Database Group